convex hull

#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>
#include <set>
#include <cmath>
#include <limits>
#include <cstring>
#include <string>
using namespace std;
typedef long long ll;
 
struct point {
    ll x, y;
    ll p = 0, q = 0;
};
 
bool cmp2(point& a, point& b) {
    if (1LL * a.p * b.q != 1LL * a.q * b.p) return 1LL * a.q * b.p < 1LL * a.p * b.q;
    if (a.x != b.x) return a.x > b.x;
    return a.y < b.y;
}
 
bool cmp(point& a, point& b) {
    if (a.x != b.x) return a.x < b.x;
    return a.y < b.y;
}
 
ll ccw(point& a, point& b, point& c) {
    return 1LL * (b.x - a.x) * (c.y - a.y) - 1LL * (b.y - a.y) * (c.x - a.x);
}
 
int N, i, x, y;
point arr[100000];
 
int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
 
    for (cin >> N; i < N; i++) {
        cin >> arr[i].x >> arr[i].y;
        char ch;
        cin >> ch;
        if (ch == 'N')N--, i--;
    }
 
    sort(arr, arr + N, cmp);
 
    for (int i = 1; i < N; i++) {
        arr[i].p = arr[i].x - arr[0].x;
        arr[i].q = arr[i].y - arr[0].y;
    }
 
    sort(arr + 1, arr + N, cmp2);
 
    stack<int> s;
 
    int next = 2;
    s.push(0);
    s.push(1);
 
    while (next < N) {
        while (s.size() >= 2) {
            int first, second;
            second = s.top();
            s.pop();
            first = s.top();
 
            if (ccw(arr[first], arr[second], arr[next]) >= 0) {
                s.push(second);
                break;
            }
        }
        s.push(next++);
    }
 
    vector<point> v;
    while (!s.empty()) {
        int idx = s.top();
        s.pop();
        v.push_back(arr[idx]);
    }
 
    cout << v.size() << endl;
    for (int i = v.size() - 1; i >= 0; i--) {
        cout << v[i].x << " " << v[i].y << "\n";
    }
 
    return 0;
}